1977 Automatic Transmission Equipped Models
- With engine cold, start engine and check for vacuum at distributor retard vacuum unit. There should be no vacuum present. If vacuum is present, disconnect thermo sensor. If vacuum remains, replace ignition solenoid valve. If vacuum drops slightly, replace thermo sensor. See Fig 1.
- With engine idling at normal operating temperature, there should be vacuum to distributor vacuum retard unit. If no vacuum is present, check for vacuum at ignition solenoid valve. If no vacuum is present at solenoid valve, clean intake manifold vacuum port.
- If there is still no vacuum at solenoid valve, check voltage at solenoid valve. If voltage is present, replace solenoid valve. If no voltage is present, check for defective delay valve, delay chamber, or vacuum switch.
- Raise engine speed to 3500 RPM. Check that vacuum to distributor vacuum retard unit is cut off within 10-40 seconds. If not, replace delay valve and recheck. If vacuum cut off time is still incorrect, replace vacuum switch.
- If vacuum to distributor vacuum retard unit is not cut off at all, disconnect ignition solenoid valve. Vacuum to distributor retard unit should be cut off. If not, replace ignition solenoid valve.
Courtesy of AMERICAN HONDA MOTOR CO., INC.